This invention relates to a method for restoring an airfoil blade, such as for a gas turbine engine.
An airfoil blade for a gas turbine engine generally experiences wear during normal engine operation. To avoid buying a new airfoil blade, it may be desirable to restore the worn airfoil blade.
With reference to FIG. 1, there is shown a prior art technique for restoring airfoil blade 10. Airfoil blade 10 has leading edge 18 spaced from trailing edge 22 and tip 26 spaced from base 30. Length L is defined between tip 26 and base 30 while width W is defined between leading edge 18 and trailing edge 22. Generally, restoration of airfoil blade 10 involves machining away thin and worn surfaces from airfoil blade body 14 to form ledge 23 with curve 25, which extends from tip 26 to one of leading edge 18 or trailing edge 22. Substantially parallel weld layers 20 are then deposited on ledge 23 by welding, such as by laser powder fusion or plasma arc welding, in the direction of arrow A from tip 26 along length L of airfoil blade 10 to curve 25. Each weld layer 20 starts at tip 26 and ends at points 21 of curve 25. However, because welding of weld layers 20 is stopped at points 21 of curve 25, air foil body 14 may melt or burn in the areas around points 21 due to excess heat from welding. Consequently, these areas of airfoil blade 10 may require rework, such as additional welding and machining of these areas, which is very time-consuming.
A need therefore exists for an improved welding technique that eliminates the welding imperfection caused by localized melting at the point of contact of the weld layer with the airfoil blade body.